If you had a platform 840mm long from the hinge and it weight was 85KGS. At the hinge the platform rotated on a 20MM shaft what would be the torque on the shaft

Assuming that the weight of the platform is uniformly distributed, its center of gravity is 0.42 m from the hinge. So the torque presented by its weight is:


T = F\ \times \ d = 85 Kg\ \times \ 9.8 m/s^2 \ \times \ 0.42 m = 350 \ N-m.

Thanks